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    <title>Document</title>
    <script>
       var afterDay = parseInt(prompt("如果今天星期二，请输入一个天数",1000));
       var week=(afterDay % 7) + 2;
       switch (week) {
            case 2:
            case 3:  
            case 4:
            case 5:
            case 6:
            alert(afterDay+"天后是星期"+week)
            break; 
            case 7:
            alert(afterDay+"天后是星期天")
            break;
            case 8:
            alert(afterDay+"天后是星期1")
            break;
       }

    </script>
</head>
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</body>
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